Jordan Ellenberg, a professor at the University of Wisconsin-Madison, created the Hawking Index (HI) to calculate how the top highlighted passages were spread through popular books, hypothesising that when people stopped highlighting, they had probably stopped reading.

Writing in the Wall Street Journal, Dr Ellenberg admitted the method was “not remotely scientific and is for entertainment purposes only” before applying it to some of the best-selling books on Amazon.

“Apparently the reading was more slow than fast,” joked Dr Ellenberg, although in fairness the author has won the Nobel Memorial Prize in Economics and the scientific tome is “at the forefront of cognitive psychology”.

Fifty Shades of Grey, still in the Amazon bestseller lists, came in the middle ground with an HI of 25.9 per cent.

All top highlights come from the last 20 pages of the Pulitzer Prize-winning novel.

Catching Fire, the second book in Suzanne Collins’ phenomenally successful Hunger Games trilogy, came in second at 43.4 per cent.

“Because sometimes things happen to people and they're not equipped to deal with them" is the most highlighted sentence in the seven-year history of Kindle, marked by 28,703 readers, according to Dr Ellenberg.

But even The Great Gatsby couldn’t keep people hooked, with an HI 0f 28.3 per cent.